I'm trying to download plugins from my VMWare IC under the Plugin Manager. But when I click download and install I keep getting an error "Unable to connect to the remote server" The server the Management is running on can access the internet...
The client from the plugin manager will try to download the plugin from your vc directly, not the internet. For some reason, you vc is not replying back with the plugin. Look in your update manager install directory, and you should be able to manually install the missing plugin for update manager (vmware-updatemgr.exe) and the converter enterprise folder for the converter plugin (vmware-converter.exe)
Are you having problems installing any plugins or just the included two that comes with the base install of VI3? If the latter, you'll want to verify that the services that you're intending to use are started on your VC server. For example, I've run into issues with the upgrade mgr install if my update manager service isn't running on the VirtualCenter server.
Just a thought for something to check in if this is the problem you're seeing with the included plugins (from the screenshot, it looks like you're trying the update manager install...).
If you found this posting to be useful, great. I didn't waste your time.
On your vc server. Go to where you installed update manager. In that location, you should see a docroot\vci\downloads location. Inside should be vmware-UMClient.exe I gave the wrong exe name. This is what the plugin manager will try to contact and download and run. If it is not present, you can also find that exe on the vc install media under \vci folder.